Just recently had a Stalker dual installed in my car and I'm having some issues with my same direction radar. I've been using handheld for the longest time now and this is my first in car moving unit so not sure if this is a common problem. Stationary works great and opposite direction front/rear works awesome. However, same direction front/rear while moving is useless. As best as I can tell, my patrol speed is accurate but target speed is totally off. Depending on the situation it sometimes tells me they're doing 130mph which isn't even close. Obviously a case of the unit adding my patrol speed and their speed together. Not a big deal as that is an easy error to recognize.

The real issue is when the error is say 8 or 9 mph which may dictate a stop or not. I've been routinely playing around with it the past few nights and I still have no confidence in it. I'll be behind a sole car on the roadway pacing it within 5 mph. Hit front radar same direction and it will tell me the car is doing say 10 mph more than me when I know for a fact he's probably doing 5 or so less than me because I'm very slowly gaining on them.

I've talked to a few of our traffic units that use the same unit in their cars and all have experienced the same issues. I don't know if this is an issue with the Stalker, our install, or ust a common problem with same direction radar in general. Any thoughts or suggestions?

PRESSHRD5COPIES

02-11-2009, 06:26 PM

I don't use moving radar, although I was certified on it about 10 years ago, so be patient with me. If I recall correctly, don't you have to be moving slower than the car ahead of you in same lane/same direction. If you are moving faster than the car ahead of you, doesn't the difference in speed get added to the first car's total speed? I may be way off because I use laser in 99.9999999999999% of my tickets.

jws8308

02-11-2009, 06:48 PM

I can't speak for Stalker units, but for my Kustom Golden Eagle w/ same lane, you have to be either traveling 3 m.p.h. slower or faster than the target vehicle in order for the feature to work. Also with my Kustom, if the target vehicle is moving 3+ m.p.h. slower than my patrol speed, I have to press and hold down the slowest button on my remote while tracking the target vehicle. This button is not required though when I am obviously traveling slower than the target vehicle.

I was however under the impression that stalker had automatic same lane features, atleast on the newer versions. Believe me though, you have a top of the line unit as any Stalker unit is a good one, IMHO.

t150vsuptpr

02-11-2009, 09:15 PM

Depending on the situation it sometimes tells me they're doing 130mph which isn't even close. Obviously a case of the unit adding my patrol speed and their speed together. Not a big deal as that is an easy error to recognize.I don't know how it can add your speed and his speed ... as it can only derive his speed by adding or subtracting the speed difference to your patrol speed in same direction mode. Short of watching what's going on when this happens, I'm at a loss to explain it.
The real issue is when the error is say 8 or 9 mph which may dictate a stop or not. I've been routinely playing around with it the past few nights and I still have no confidence in it. I'll be behind a sole car on the roadway pacing it within 5 mph. Hit front radar same direction and it will tell me the car is doing say 10 mph more than me when I know for a fact he's probably doing 5 or so less than me because I'm very slowly gaining on them. So to get it straight .... you are running 65, believe him to be running slightly slower like less than 5 under your speed, but radar says 75?

Easy ... You'r Stalker is ignoring him, it's reading someone way on up the road running either 10 mph over or under your speed. You'll never know which either without doing a speed discrimination test.

Please, if not thoroughly trained in the use of that radarby an instructor in same direction mode, and if not absolutely sure that you understand what it's doing, please refrain from taking enforcement action. Same direction radar is the easiest to get wrong, and getting it wrong isn't worth the hardfeelings and injustice that can result.

I can't speak for Stalker units, but for my Kustom Golden Eagle w/ same lane, you have to be either traveling 3 m.p.h. slower or faster than the target vehicle in order for the feature to work. Also with my Kustom, if the target vehicle is moving 3+ m.p.h. slower than my patrol speed, I have to press and hold down the slowest button on my remote while tracking the target vehicle. This button is not required though when I am obviously traveling slower than the target vehicle.

I was however under the impression that stalker had automatic same lane features, atleast on the newer versions. Believe me though, you have a top of the line unit as any Stalker unit is a good one, IMHO.It's 4-5 mph with my Golden Eagle, it ignors everything within 3-4 mph of my patrol speed in same direction mode (it'll read a 69-70 and up at 65 patrol). Minor thing. :)

Maybe you just left it out as not germain to the thread subject, I don't know .... but let me just add to that the following without it being taken as a correction. It's simply an explanation for readers and it may help the opening poster, Airforcop .....

While you may be intending to track that faster car overtaking you, the radar may in fact be tracking a slower tractor trailer another 1/2 mile further back, etc ....

It is why in same direction mode you must perform a speed discrimination test.

Illustration .... you are in patrol vehicle at 65 mph, see car overtaking you, looks like near 75-80. Let us assume he is in fact running exactly 80, you just don't know that yet. Also unbeknownst to you, even further back is a tractor trailer that merged at that lst exit, he's making 50 mph.

Now, the Golden Eagle will read your ground speed or "patrol" speed as 65. Whether it's reading that far away truck falling back at 15 mph relative to you'r car or whether it's reading that closer car overtaking you at 15 mph relative speed, it's programmed to add that 15 to your "patrol" speed and report it as "target" speed.

And until you do a speed discrimination test, you will not know.

When you then do the speed discrimination test, you change your patrol speed up and down by a few mph. If you accelerate to say 68 mph, the patrol display will also go up to 68. If the target speed stays steady at 80, you are indeed tracking the faster car or some vehiocle at 80 mph on the rear antenna, as now the relative speed or "speed difference" is only 12 because he stayed at 80 when you hit 68, and it adds that 12 to the 68 and target remains unchanged because it didn't change.

If however, when you added those 3mph to patrol speed by accelerating, the target speed went up by several mph also like say to 86, then that's a sign that something isn't just what it seems, you are likely tracking a slower vehicle instead and it was that 50 mph tractor trailer likely, for when you hit 68, and his speed didn't change with yours, you are now running 18 mph faster than he and it adds that 18 back to the 68 and shows a target of 86 now.

Good time to slow down now to like 63, and you'll likely find the target speed drop 2 mph for every 1 mph drop in pattrol, as at 62 with him still running 50, it adds 12 then to the 62 and shows target as 74. The reason for both slowing and speeding up, or "vice-versa" is that it's possible for another person to also be changing speed when you are, but it's not so likely that he'll both speed up and slow down while overtaking you and do it at the same time you do.

That guy catching you might be running, might be doing 80, but you are not tracking him with radar.

Using the "fastest" button while doing the speed discrimination test will reverse the results as now you are telling the unit to subtract the speed difference or "relative speed" from your ground or "patrol" speed. With the button depressed, it's the slower vehicle which will result in no change in speed as you go through the speed discrimination tests, and the faster vehicle which will exhibit a change in target speed.

There is no circumstance where I would issue a summons for speeding to the driver of a vehicle traveling slower than my patrol vehicle at the time of detection unless his limit was way lower than mine.

:)

jws8308

02-11-2009, 09:39 PM

So to get it straight .... you are running 65, believe him to be running slightly slower like less than 5 under your speed, but radar says 75?

Easy ... You'r Stalker is ignoring him, it's reading someone way on up the road running either 10 mph over or under your speed. You'll never know which either without doing a speed discrimination test.

Please, if not thoroughly trained in the use of that radarby an instructor in same direction mode, and if not absolutely sure that you understand what it's doing, please refrain from taking enforcement action. Same direction radar is the easiest to get wrong, and getting it wrong isn't worth the hardfeelings and injustice that can result.

It's 4 mph with my Golden Eagle. Minor thing. :)

Maybe you just left it out as not germain to the thread subject, I don't know .... but let me just add to that the following without it being taken as a correction. It's simply an explanation for readers and it may help the opening poster, Airforcop .....

While you may be intending to track that faster car overtaking you, the radar may in fact be tracking a slower tractor trailer another 1/2 mile further back, etc ....

It is why in same direction mode you must perform a speed discrimination test.

Illustration .... you are in patrol vehicle at 65 mph, see car overtaking you, looks like near 75-80. Let us assume he is in fact running exactly 80, you just don't know that yet. Also unbeknownst to you, even further back is a tractor trailer that merged at that lst exit, he's making 50 mph.

Now, the Golden Eagle will read your ground speed or "patrol" speed as 65. Whether it's reading that far away truck falling back at 15 mph relative to you'r car or whether it's reading that closer car overtaking you at 15 mph relative speed, it's programmed to add that 15 to your "patrol" speed and report it as "target" speed.

And until you do a speed discrimination test, you will not know.

When you then do the speed discrimination test, you change your patrol speed up and down by a few mph. If you accelerate to say 68 mph, the patrol display will also go up to 68. If the target speed stays steady at 80, you are indeed tracking the faster car or some vehiocle at 80 mph on the rear antenna, as now the relative speed or "speed difference" is only 12 because he stayed at 80 when you hit 68, and it adds that 12 to the 68 and target remains unchanged because it didn't change.

If however, when you added those 3mph to patrol speed by accelerating, the target speed went up by several mph also like say to 86, then that's a sign that something isn't just what it seems, you are likely tracking a slower vehicle instead and it was that 50 mph tractor trailer likely, for when you hit 68, and his speed didn't change with yours, you are now running 18 mph faster than he and it adds that 18 back to the 68 and shows a target of 86 now.

Good time to slow down now to like 63, and you'll likely find the target speed drop 2 mph for every 1 mph drop in pattrol, as at 62 with him still running 50, it adds 12 then to the 62 and shows target as 74. The reason for both slowing and speeding up, or "vice-versa" is that it's possible for another person to also be changing speed when you are, but it's not so likely that he'll both speed up and slow down while overtaking you and do it at the same time you do.

That guy catching you might be running, might be doing 80, but you are not tracking him with radar.

Using the "fastest" button while doing the speed discrimination test will reverse the results as now you are telling the unit to subtract the speed difference or "relative speed" from your ground or "patrol" speed. With the button depressed, it's the slower vehicle which will result in no change in speed as you go through the speed discrimination tests, and the faster vehicle which will exhibit a change in target speed.

There is no circumstance where I would issue a summons for speeding to the driver of a vehicle traveling slower than my patrol vehicle at the time of detection unless his limit was way lower than mine.

:)

+1

Thanks for the clarification. I take your word to the fullest extent on this topic, trooper :D. I have found that the speed difference is atleast 3 m.p.h. but you would be correct with 4 m.p.h. as I think that would be more accurate. I think it depends on the units too as told to me by a repair shop as I have an older Ka Band Golden Eagle. I also hardly use the function due to my ignorance in its use. I am used to old school radars, and when this new technology came out, I have been trying to get used to it. I have used same lane before on low speed roads when approaching someone from the rear, I would be traveling at a speed greater than the target vehicle and I would use my same lane with the slower button depressed. Upon getting my speed readout, I would pace the vehicle (they didn't suspect me in an unmarked truck) and compare the results to a certain extent. I just felt that a speed obtained by radar would be held to a higher standard then my speedometer. On the flip side, I don't run radar that much and if so, it is always on low speed roads, never on interstates. I hardly site for same lane violations, let alone opposite :p.

t150vsuptpr

02-11-2009, 10:29 PM

jws8308, I'm glad you didn't take my post the wrong way.

I reworded it several times, my intent was only to add to what you said to maybe help Airforcop.

:)

ChopperCopper

02-11-2009, 10:29 PM

Don't forget: Size, Reflectivity, Distance

J_Mann

02-12-2009, 02:21 AM

I use the stalker dual dsr. I'm certified to run radar and lidar. I have a 40 hour training class on how to use and operate, etc. on radar and lidar. I have 16 hours of training during FTO on the stalker dual dsr's. I use it everyday. I NEVER use same direction. Too many problems. Other than that, GREAT radar units.

usmcrob

02-12-2009, 10:29 AM

I would contact Stalker. We have been using the DSR 2X for quite a while now and have had very few problems. Any problems that did arise, Stalker quickly took care of. Most of us use same direction radar as we drive stealth vehicles. The Stalker has a 3-4 mph difference in same direction mode, meaning that it won't detect if the target vehicle is within 3-4 mph of the patrol speed.

wirefire2

02-12-2009, 07:20 PM

Same direction is tricky, if you have more than one target the radar will bounce between targets and give you a screwy reading.

Make sure the antenna is sitting level.

Don't be afraid to call the stalker people, I would also make sure the sensitivity is turned up (or you may need to turn it down for a close contact) and your minimum speed setting is at 5mph and not at 20mph.

Lastly make sure your speedometer is accurate.

firebirdconv92

02-18-2009, 01:20 PM

I'm issued a Decatur (forgive spelling) dual head unit with the same direction feature. I usually have to be traveling approximately 5 mph faster or slower than the target vehicle for it to work properly. I've written a couple tickets using it and every time I've advised the driver the speed I had them clocked at they've agreed with it.

But again, use your judgement.

KAA951

02-18-2009, 05:46 PM

I have had 14 years of operating a dual Stalker radar on a daily basis and use the same lane mode all the time. As Trooper stated above, with the older version of the Stalker you had to discriminate as to whether the vehicle you were checking was going faster or slower than you were. It took a good, experienced operator to use same lane correctly.

However, the newer model Stalker dual we moved to about 3 years ago does not have those issues and uses a VSS cable. The newer Stalker can tell if the vehicle is going faster / slower in same lane and automatically determines if you are in moving or stationary mode.